Fuse cutout



Aug` 16: 1960 y J. R. McBRlDE 2,949,517

' FUSE:k cUToUT Filed July 2l, 1958 H6133 f 5,0 F162,

2 Sheets-Sheet l;

Aug. 16, 1960 Filed July 2l, 1958 J. R. MCBRIDE FUSE CUTOUT 2 Sheets-Sheet 2 United tates Patent i" ce FUSE CUTUT Joseph R. McBride, Centraiia, Mo., assignor to A. B.

Chance Company, Centralia, Mo., a corporation of Missouri This invention relates to fuse cutouts, and more particularly to enclosed type fuse cutouts.

Among the several objects of the invention may be -noted the provision of a fuse cutout which will operate to break an electrical circuit even when subject to extremely high fault currents; the provision of apparatus of this class which will selectively indicate rupture of its fuse link by either dropout action of its door or by an indicator ag without opening of the door; the provision of a fuse cutout in which' shock damage to the door and housing thereof is entirely eliminated; the provision of a fuse cutout of this class in which the door can be completely installed and removed from any of a wide range of angles or positions with a standard hookstick; the provision of such a fuse cutout in which the terminals, mounting hanger and trunnions for the door are anchored to the housing by la tough, shockresistant, resilient material; and the provision of a fuse cutout which is rugged in construction and reliable in operation. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the constructions hereinafter described, the scope of the invention being indicated in the following claims.

In the accompanying drawings, in which is illustrated one of various possible embodiments of the invention,

Fig. l is a longitudinal section of a fuse cutout of this invention, certain internal parts being shown in elevation, prior to rupture of the fuse link; the position of the parts after rupture of the fuse link in non-dropout operation being shown in dotted lines;

Fig. 2 is an inside view of the door assembly of the fuse cutout of Fig. l showing the fuse link after rupture and the indicating flag in its released position;

Figs. 3-5 are cross sections taken on lines 33, 4--4 and 5--5, respectively, of Fig. l; and

Fig. 6 is a view similar to Fig. 1 but illustrating the position of the door after rupture of the fuse link in dropout operation.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Referring now more particularly to the drawings, a fuse cutout housing7 or box of porcelain or similar insulating `material is indicated at reference numeral 1. Box 1 is ribbed as shown at 3 to provide high dielectric strength, and includes a rear wall 57 a top wall 7 and i's enclosed on two sides by walls 9 and 11, the front and bottom of the box being open. The forward edge of the 'side and top walls is rabbeted to provide a forwardly extending lip lil. Rear wall 5 has a rearwardly opening socket or well into which a mounting bracket 15 is cemented by means of a body of tough, resilient, shock-resistant cured epoxy resin as indicated yat 17. Another well l21, opening in a forward direction, is located adjacent the `lower edge of Arear wall 5. Secured by means of a mass of cured epoxy resin 19 in well Patented Aug. 16, 1960 21 are a pair of forwardly projecting elongate cantilever arms 23 preferably made of a spring steel and bent in the form of a C, the forward ends of the arms being bent so as to be directed toward each other, forming pivots 25, the leg of the C and rear portions of the arms of the C being embedded in resin body 19. Rear wall 5 has two additional forwardly opening sockets or recesses 27 and 29 into which are secured idential lower and upper L-shaped terminal brackets 31 and 33, respectively, by means of additional bodies of cured epoxy resin material.

The mounting bracket 15, the spring cantilever arms 23 and the upper and lower terminal anchors 31 and 33 are secured to the rear wall of housing 1 by pouring into their respective wells a liquid mixture made by intermixing parts by weight of an epoxy resin (such as that sold by Shell Chemical Corporation under the trade designation Epon 828, or any other similar conventional epoxy resins, such `as that sold by Jones-Dabney Co. under the trade designation Epi-rez 550"), 200 parts by weight of ground calcium carbonate and lO parts by weight of a coloring agent (such as that sold by the G. K. Williams Company under the trade designation Bu 8363), and then heating said mixture to about F. and adding 20 parts by weight of an epoxy resin curing agent (such as that sold by Shell Chemical Corporation under the trade designation Curing Agent U). The aforementioned brackets, terminal anchors and cantilever arms are held in position by jigs, etc., so that the liquid level of tlhe epoxy resin mixture in the wells is such as indicated in the drawings. After about 3 4 hours at room temperature, the epoxy resin mixture becomes cured, thereby forming a tough, resilient and shock-absorbing base for bracket 15, cantilever arms 23 and terminal anchors 31 and 33.

The forward faces of anchors 31 and 33 constitute fixed jaws which clampingly engage lower and upper line conductors 35 and 37 by means of two movable jaws 39 and 41. Clamping pressure is applied to jaws 39 and 41 by means of screws 43 which are threaded in and project through channel-shaped lower and upper terminals 45 and 47. The upper ends of terminals 45 and 47 comprise tangs 49 engaged in slots 51 of the terminal anchors, While the lower ends of terminals 45 and 47 are constituted by apertured flanges 53. A screw 5S threaded in the lower end of the upper terminal anchor 33 functions to secure a latch 57 and an upper Contact 59, as well as the flange portion 53 of tenminal 47, to `anchor 33. A screw 61 threaded in the lower end of lower terminal anchor 31 similarly secures a lower contact 63 and the ange portion 53 of lower terminal 45 to anchor 31. Lower contact 63 comprises two forwardly extending arms, the outer portions of which flare outwardly and downwardly and constitute lower Contact surfaces 65. Upper contact 59 comprises two forwardly extending arms, the outer portions of which are of reentry form and constitute conltact surfaces `67 which diverge in a forward direction.

Latch 57 includes two forwardly extending lateral arms with downwardly 4directed catches 69.

A door assembly for the front opening of box 1 is indicated generally at numeral 70. The door assembly is quick-detachably pivotally supported at its lower end on the pivots 25 of the resilient cantilever arms 23, by means of hook-shaped recesses 71 in a U-shaped hinge bracket 73. Hinge bracket 73 of conductive metal is provided with aligned apertures 75 in its side walls 66 adjacent the upper and forward edges thereof. A door 77 of insulating material, such as cast thermosetting phenolic resin, is pivotally connected to hinge bracket 73 by vmeans of a retaining or cross ypin 79 of spring steel. The outer ends of pin 79 are journalled in the aligned apertures 75 and the pin traverses two holes 81 1u rearwardly extending ears 83 formed integrally in longitudinal reinforcing ribs 85' on the inside surface of door 77. The holes S1 are large in relation to the cross Sectlon of pin 79, thereby providing a loose coupling and a lost-motion connection between door 77 and hinge member 73. Rotation of door 7'7 relative to hinge member 73 may be selectively restricted by the optional use of a screw 84 threaded in the side wall of one of the ribs 85.

Between the ribs 85 on the inside surface of door 77 is a fuse assembly S7 comprising a fuse tube 89 of insulatlng materials, such -as a combination of liber glass and horn fiber, slidable and loosely mounted on the door at 1ts upper end by means of a yoke 91. A tube clamp 93 encompasses a lower portion of the fuse tube and is provided with a Itransverse hole 95 to receive the central portion of cross pin 79. The lower end of `fuse tube 89 is connected to cross pin 79 by means of a transverse slot in the forward surface thereof. By tightening a screw 97 the center of pin 79 is rigidly secured to tube S9. The top end of the fuse tube is equipped with a metal ferrule 99 constituting an upper terminal-engaging contact atlxed to the tube by drive pins 101.

Ferrule 99 terminates in a collar 103 on which is threaded a knurled thumb cap 105. Fuse tube 89 is adapted to receive a conventional replaceable fuse link, -the upper' end or head of which is mechanically and electrically secured to ferrule 99, and the lower end of which comprises a iiexible stranded-wire pigtail 107. This pigtail 107 is attached to the hinge member by a thumbscrew 1539 threaded in hinge bracket 73.

The portion of pigtail 1117 between screw 109 and the lower end of the fuse tube is tensioned by a link ejector constituted by a lever 111 having two arms 113 and 115. Arm 113 is provided with a groove 118 at its outer end which engages a portion of the pigtail. The other arm 115, which extends from arm 113 at right angles thereto, .carries an indicator flag 117 pivotally mounted at 119 at 1ts outer extremity. The link ejector lever 111 is pivoted on 'a cross pin 120, the ends of which are received in apertures 121 formed in one side wall of hinge bracket 73 and in a bent-over ear 123 at the lower edge of hinge 73. A coil spring 125 surrounding pin 120 has an end portion 127 engaged with the hinge and its other end portion 129 engageable with lever 111 tending to cause it to swing :down and thereby tension the pigtail.

Door 77 is also provided `at the upper end of each o-f the spaced longitudinal ribs 35 with a detent 131, each adapted to be engaged by one of the spaced downwardly directed catches 69, thereby latching door 77 in its generally upright position closing the front opening of housing 1. In order to permit complete hookstick operation of this enclosed cutout by the lineman, a door handle 133 with a large eye is provided on the outer surface of the door adjacent its upper end, whereby the door can be easily opened by engaging and pulling on handle 133 with the conventional hookstick. After opening the door, thereby breaking the electrical connections between the upper and lower terminals and the fuse tube ferrule and hinge bracket respectively, the entire door yassembly 70 may be completely removed by engaging the end of a hookstick in a keyhole-shaped recess 135 in the web of the hinge bracket 73. Thus the door can be lifted completely free of the housing by a hookstick from a Wide range of angles and similarly reinstalled by positioning the door on the trunnions or pivots 25.

It is prefer-red, at least in the heavier duty sizes of these cutouts, to provide a gas barrier 137 positioned around the fuse tube 89 intermediate its ends. This gas barrier is an insulating pad, such as foam rubber or an expanded synthetic resin material, and when door 77 is :in a closed position barrier 137 is forced against a web 139 Abetween side walls 9 and 11 of porcelain housing 1,

thereby forming two `separate compartments therein, one on the top including the upper terminal and contacts and the other at the bottom including the lower terminal and hinge bracket, etc.

Operation -is as follows:

Assuming that door 77 is closed and screw 84 is threaded in rib iid (thereby locking door 77 against pivotal movement relative to hinge bracket 73 around the axis of cross pin 79), upon the flow of currents through line conductors 35 and 37 exceeding the rating of the fuse link, the lat-ter element will rupture. The tension applied to the pigtail 1117 by spring and link ejector lever 111 will cause the bottom portion of the ruptured -link to be rapidly ejected from the bottom opening of fuse tube 89, thereby aiding in extinguishing the arc. inasmuch as pigtail 1117, one end of which is caught under thumbscrew 109, also functions to prevent rotation of lever 111 until rupture of the fuse link, this lever 111 will rotate downwardly and outwardly, permitting indicator flag 117 (which normally stays tucked inside the box) to swing downwardly and project below the bottom opening of the box (Fig. l, dotted-line position). Door 77 stays closed and the line crew may spot the outage by the visual indication of the flag.

If the fault current that causes rupture of the link is exceptionally high (such as would be caused by a dead short across the lines), say on the order of 5000 to 10,000 amps., the rupture of the 4fuse link is literally explosive and tends to forcefully propel fuse tube 89 upward Iby expulsion of the gases. Without the features of the present invention, the resultant recoil of the tube would carry door '77 upward and the shock of the expulsion, or the impact of the door against the protective lip 10 of the housing 1, could shatter the door and/or the housing. However, in accordance with the present invention, shock damage to the plastic `door or the porcelain housing is entirely eliminated even when the cutout operates under recoil impact of the highest fault currents. This is accomplished by the cantilever spring arms 23 and the shock-absorbing lost-motion connection between the fuse tube 89 and hinge member 73 via cross pin 79. As tube 89 is propelled upwardly it will bow the center of cross pin 79 upwardly. Because of the very loose it of pin 79 in the holes 31 through ears S3, the door will not follow the motion of tube 39 but the latter will slide upwardly relative thereto. The shock is therefore directly transferred to the hinge bracket 73 and its sudden upward movement is resisted by the shock-absorbing resilient trun'nions or cantilever arms 23, on which hinge bracket 73 is pivotally mounted. As the rearward ends of the rtunnions or arms are firmly embedded in the tough, resilient, cured resin mass 19, it will be seen that the recoil impact is dissipated without damage to the housing 1 or door 77. Although any upward movement of the door 77 would be `delayed and damped, 4it will be noted that space is provided as indicated at numeral 141 so that the upper edge lof `door 77 is spaced :from the lower surface of the top portion of the housing flange or lip 10 a distance greater than that which would be traversed by the door during recoil. Also, the ionized gas generated when the cutout operates is sealed off from the top terminal 47 by means of the optional gas barrier, so no arc may be established across the terminals of the cutout.

In order to replace the fuse link, the lineman merely opens door 77 by engaging the end of his hookstick in the eye of door handle 133 and pulls, thereby permitting the door to drop down exposing the keyhole-shaped recess in the hinge bracket 73. This opening action also electrically disconnects ferrule 99 and hinge bracket 73 from the upper and lower terminals. The door is retained on the pivots 25 by the hook-shaped apertures 71 until the lineman lifts door 77 olf of pivots 25. After the fuse link is replaced, the ejection lever 111 and indicator ag 117 are rotated upwardly inside the hinge bracket 73 and retained there against the bias of coil spring 125 by the `gripping action of thumbscrew 109 on the outer end of pigtail 107.- The door assembly 70 with the' new fuse link is then hooked onto pivots Z5 and closed by the linemans hookstick.

Under certain conditions, it is desirable to have dropout action of the door upon rupture of the fuse link. To accomplish this, the lineman simply removes screw 84, thereby permitting relative rotation between hinge bracket 73 and door 77 about the axis of cross pin 79. The shock-absorbing action described above upon rupture of the fuse link is duplicated in dropout operation, but rupture of the fuse link (thus releasing the biasing action of spring 125 and lever 111 against pigtail 107) permits the bottom of door 77 to move downwardly and outwardly. The flared contact surfaces 65 and `67 also bias door 77 downwardly and outwardly, thereby moving detents 131 out of engagement with catches '69 of latch 57. Door 77, then freed of restraint by latch 57, swings out and down as shown in Fig. 6; Removal of the door assembly 70, replacement of the link and reinstallation of the door assembly are accomplished as noted above by a hot stiok.

Iii view of the above, it will be seen that the several objects of the invention are achieved and `other advantageous rlesultsattained.

As various changes could be made in the above constructions without departing from the scope of the invention, 4it is intended that al1 matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. A fuse cutout comprising a box, shock-absorbing cantilever spring 'arms carried by the box, a door `for the box, a hinge member pivotally mounting said door on said spring arms, a fuse tube including a fuse link mounted on the door, and shock-absorbing means connecting said fuse tube and said hinge member whereby upon blowing of the fuse link the resultant recoil of the fuse tube is transferred directly through said shock-absorbing connecting means to said hinge member and thence to said shockabsorbing pivot means.

2. A fuse cutout as set forth in claim 1, wherein said hinge member has a llost-motion pivotal connection to the door.

3. A fuse cutout comprising a box having a rear wall, side walls, and a top wall and being open at the front and the bottom, a pair of cantilever spring arms extending forwardly from the rear Wall adjacent the bottom of the box, the forward ends of the arms being formed to` provide pivots, `a door for closing the front of the box,

a hinge member having a lost-motion connection to said door, said hinge member being pivotally supported by said pivots at the forward ends of said spring arms, a fuse tube including a fuse link slidably mounted on the inside of the door, and shock-absorbing means connecting said fuse tube and said hinge member whereby upon blowing of the fuse link the resultant recoil of the fuse tube is transferred directly through said shock-absorbing connecting means to said hinge member and thence to said shock-absorbing pivot means.

4. A fuse cutout comprising a box having a rear wall, side walls, and a top wall and being open at the front and the bottom, a pair of cantilever spring arms extending forward from the rear wall adjacent the bottom of the box, the forward ends of the arms being formed to provide pivots, a door for closing the front of the box, said door having a pair of ears on the inside thereof, said ears having holes therein, a hinge member having a pair of spaced apertures therein aligned with said holes, a pin extending through said holes and said apertures thereby providing a lost-motion connection between the hinge member and the door, said hinge member being pivotally supported by said pivots at the forward ends of said spring arms, and a fuse tube including a fuse link slidably mounted on the inside of the door between said ears and having a connection with Said pin whereby upon blowing of the fuse link the resultant recoil of the fuse tube is transferred directly through said pin to said hinge member and thence to said cantilever spring arms.

5. A fuse cutout as set forth in claim 4, wherein said holes are substantially larger than the cross section of said pin.

6. A fuse cutout as set forth in claim 4, wherein said pin is resilient thereby providing a shock-absorbing lostmotion connection between the hinge member and the door.

7. A fuse cutout as set forth in claim 4, wherein said hinge member is pivotally connected by said pin to the door.

8. A fuse cutout as set forth in claim 7, which further includes means for selectively locking the pivotal connection between said door and hinge member whereby said hinge member may be connected to said door in a predetermined position.

9. A fuse cutout as set forth in claim 4, wherein said hinge member has `a quick-detachable connection to said pivot means.

10. A fuse cutout as set forth in claim 7 in which said top and side walls have an outer ilange extending forwardly past the inner surface of said door, the portion of said ange at the top wall being spaced from the upper end of the door a distance greater than that traversed by the door during recoil.

1l. A fuse cutout as set forth in claim 7 in which said rear wall has two wells opening forward and in which said upper and lower terminals are aflixed by a body of cured epoxy resin, a third forwardly opening well in which the rearward ends of said cantilever spring arms are cemented by a body of cured epoxy resin, and a fourth Well opening rearwardly and having a mounting bracket anchored therein with a body of cured epoxy resin.

12. A fuse cutout comprising a box having a rear wall, Side Walls, and a top Wall and being open at the front and the bottom, upper and lower terminals extending forward from the rear wall of the box, a pair of cantilever spring arms extending forward from said rear wall adjacent the bottom of the box, the forward ends of the arms being formed to provide pivots, a door for closing the front of the box, a hinge member having a lost-motion connection to said door, said hinge member being pivotally supported by said pivots at the forward ends of said spring arms, a fuse tube slidably mounted on the inside of the door, shock-absorbing means connecting said fuse tube and said hinge member, an upper terminal-engaging contact at the upper end of the fuse tube, and a fuse link in said tube electrically connected between said contact and said hinge member, said contact and hinge means being respectively engageable with said upper and lower terminals upon closure of the door whereby upon blowing of the fuse link the. resultant recoil of the fuse tube is transferred directly through said shock-absorbing connecting means to said hinge member and thence to said cantilever spring arms.

13. A fuse cutout as set forth in claim 12, wherein said door has a pair of ears on the inside thereof, said ears having holes therein, said hinge member having a pair of apertures therein aligned with said holes, a resilient pin of substantially lesser cross sectional area than said holes extending through said holes and said apertures thereby providing a lost-motion pivotal connection between the hinge member and the door.

14. A fuse cutout as set forth in claim 13, which further includes means for selectively locking the pivotal connection between said door and hinge member whereby said hinge member may be connected to the door in a predetermined position.

15. A fuse cutout as set forth in claim 13, wherein said hinge member has a quick-detachable connection to said pivots.

16. A fuse cutout as set forth in claim 13, wherein said hinge member is Ushaped, having the opening of the U facing forwardly, and said lower terminal has a pair of Opposed contact surfaces flaring forward and downward and adapted to make self-wiping electrical Contact with said hinge member.

17. A fuse .cutout as Set forth in claim 16, wherein said upper terminal has a pair of opposed forwardly diverging contact surfaces adapted to make self-wiping electrical contact with said upper terminal-engaging contact of said fuse tube.

18. A fuse cutout as Set forth in claim 17, wherein said door has detents on its inner surface adjacent the top thereof, and latch means adapted to engage said detents and hold said door in a normally closed position.

19. A fuse cutout as set forth in claim 13, wherein said hinge member comprises a U-shaped bracket having the opening of the U facing forwardly, and fuse link ejector means biasing the end of the fuse link connected to said hinge member in a direction away from the upper end of the fuse tube.

20. A fuse cutout as set forth in claim 19, in which said fuse link ejector includes indicator means pivotally connected therewith whereby upon rupture of said fuse link said door remains closed and said indicator means rotates to a position wherein it projects downward from the bottom opening of the box.

21. A fuse cutout comprising a box having a rear wall, a pair of generally parallel resilient shock-absorbing cantilever spring arms extending forwardly from said rear wall, said arms having forward ends formed to provide coaxial pivots with the pivot axis transverse to said arms, a door for the box, an elongate fuse tube including a fuse link adapted to be carried by the door, said fuse tube connected adjacent one end to a hinge member, said hinge member' having hooks engaging said pivots whereby upon blowing of the fuse link the resultant recoil of the fuse tube is transferred directly through said hinge member to the cantilever spring arm pivots. which thereby absorb the recoil shock by bending and torsional twisting of said arms.

22. A fuse cutout comprising a box having a rear Wall, shock-absorbing pivot means carried by the box, said pivot means comprising a length of resilient springy material bent to provide a base portion and a pair of generally parallel cantilever spring arms extending from the ends of said base portion, said base portion being secured to the rear wall of the box with said arms extending forwardly therefrom, said arms having end portions bent to form coaxial pivots with the axis thereof transverse to said arms, a door for the box, an elongate fuse tube including a fuse link adapted to be carried by the door, said fuse tube connected adjacent one end to a hinge member, said hinge member having hooks engaging said pivots at points spaced from said arms whereby upon blowing of the fuse link the resultant recoil of the fuse tube is transferred directly through said hinge member to the cantilever spring arm pivots which thereby absorb the recoil shock by bending and torsional twisting of said arms.

References Cited in the file of this patent UNITED STATES PATENTS 2,081,813 Hermann May 25, 1937 2,081,814 Hermann May 25,1937 2,081,826 Lincks May 25, 1937 2,183,083 Rawlins Dec. 12, 1939 2,246,807 McCluskey et al June 24, 1941 2,385,473 Schultz Sept. 25, 1945 2,651,694 Lindell Sept. 8, 1953 2,834,855 Carpenter et al May 13, 1958 

